import java.util.Scanner;

public class TestC {
    public static void main(String[] args) {
        double r,v;
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()){
            r = sc.nextDouble();
            v=(double)4/3*3.1415*(r*r*r);
            System.out.printf("%.3f",v);
            System.out.println();
        }

    }
}
